man/man1/rtcontrib.1

.\" RCSid "$Id: rtcontrib.1,v 1.13 2005/10/06 16:28:59 greg Exp $"
.TH RTCONTRIB 1 5/25/05 RADIANCE
.SH NAME
rtcontrib - compute contribution coefficients in a RADIANCE scene
.SH SYNOPSIS
.B rtcontrib
[
.B "\-n nprocs"
][
.B \-fo
|
.B \-r
][
.B "\-e expr"
][
.B "\-f source"
][
.B "\-o ospec"
][
.B "\-b binv"
][
.B "\-bn nbins"
]
{
.B "\-m mod | \-M file"
}
..
[
.B $EVAR
]
[
.B @file
]
[
rtrace options
]
.B octree
.br
.B "rtcontrib [ options ] \-defaults"
.SH DESCRIPTION
.I Rtcontrib
computes ray contributions (i.e., color coefficients)
for objects whose modifiers are named in one or more
.I \-m
settings.
These modifiers are usually materials associated with
light sources or sky domes, and must directly modify some geometric
primitives to be considered in the output.
A modifier list may also be read from a file using the
.I \-M
option.
The RAYPATH environment variable determines directories to search for
this file.
(No search takes place if a file name begins with a '.', '/' or '~'
character.)\0
.PP
The output of
.I rtcontrib
has many potential uses.
Source contributions can be used as components in linear combination to
reproduce any desired variation, e.g., simulating lighting controls or
changing sky conditions via daylight coefficients.
More generally,
.I rtcontrib
can be used to compute arbitrary input-output relationships in optical
systems, such as luminaires, light pipes, and shading devices.
.PP
.I Rtcontrib
calls
.I rtrace(1)
with the -oTW option to calculate the daughter ray
contributions for each input ray, and the output tallies
are sent to one or more destinations according to the given
.I \-o
specification.
If a destination begins with an exclamation mark ('!'), then
a pipe is opened to a command and data is sent to its standard input.
Otherwise, the destination is treated as a file.
An existing file of the same name will not be clobbered, unless the
.I \-fo
option is given.
If instead the
.I \-r
option is specified, data recovery is attempted on existing files.
If an output specification contains a "%s" format, this will be
replaced by the modifier name.
The
.I \-b
option may be used to further define
a "bin number" within each object if finer resolution is needed, and
this will be applied to a "%d" format in the output file
specification if present.
The actual bin number is computed at run time based on ray direction
and surface intersection, as described below.
If the number of bins is known in advance, it should be specified with the
.I \-bn
option, and this is critical for output files containing multiple values
per record.
Since bin numbers start from 0, the bin count is always equal to
the last bin plus 1.
Set the this value to 0 if the bin count is unknown (the default).
The most recent
.I \-b,
.I \-bn
and
.I \-o
options to the left of each
.I \-m
setting affect only that modifier.
(The ordering of other options is unimportant.)\0
.PP
If a
.I \-b
expression is defined for a particular modifier,
the bin number will be evaluated at run time for each
ray contribution from
.I rtrace.
Specifically, each ray's world intersection point will be assigned to
the variables Px, Py, and Pz, and the normalized ray direction
will be assigned to Dx, Dy, and Dz.
These parameters may be combined with definitions given in
.I \-e
arguments and files read using the
.I \-f
option.
The computed bin value will be
rounded to the nearest whole number.
This mechanism allows the user to define precise regions or directions
they wish to accumulate, such as the Tregenza sky discretization,
which would be otherwise impossible to specify
as a set of RADIANCE primitives.
The rules and predefined functions available for these expressions are
described in the
.I rcalc(1)
man page.
Unlike
.I rcalc,
.I rtcontrib
will search the RADIANCE library directories for each file given in a
.I \-f
option.
.PP
If no
.I \-o
specification is given, results are written on the standard output in order
of modifier (as given on the command line) then bin number.
Concatenated data is also sent to a single destination (i.e., an initial
.I \-o
specification without formatting strings).
If a "%s" format appears but no "%d" in the
.I \-o
specification, then each modifier will have its own output file, with
multiple values per record in the case of a non-zero
.I \-b
definition.
If a "%d" format appears but no "%s", then each bin will get its own
output file, with modifiers output in order in each record.
For text output, each RGB coefficient triple is separated by a tab,
with a newline at the end of each ray record.
For binary output formats, there is no such delimiter to mark
the end of each record.
.PP
Input and output format defaults to plain text, where each ray's
origin and direction (6 real values) are given on input,
and one line is produced per output file per ray.
Alternative data representations may be specified by the
.I \-f[io]
option, which is described in the
.I rtrace
man page along with the associated
.I \-x
and
.I \-y
resolution settings.
In particular, the color ('c') output data representation
together with positive dimensions for
.I \-x
and
.I \-y
will produce an uncompressed RADIANCE picture,
suitable for manipulation with
.I pcomb(1)
and related tools.
.PP
If the
.I \-n
option is specified with a value greater than 1, multiple
.I rtrace
processes will be used to accelerate computation on a shared
memory machine.
Note that there is no benefit to using more processes
than there are local CPUs available to do the work, and the
.I rtcontrib
process itself may use a considerable amount of CPU time.
.PP
Options may be given on the command line and/or read from the
environment and/or read from a file.
A command argument beginning with a dollar sign ('$') is immediately
replaced by the contents of the given environment variable.
A command argument beginning with an at sign ('@') is immediately
replaced by the contents of the given file.
.SH EXAMPLES
To compute the proportional contributions from sources modified
by "light1" vs. "light2" on a set of illuminance values:
.IP "" .2i
rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
.PP
To generate a pair of images corresponding to these two lights'
contributions:
.IP "" .2i
vwrays -ff -x 1024 -y 1024 -vf best.vf |
rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
.PP
These images may then be recombined using the desired outputs
of light1 and light2:
.IP "" .2i
pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
.PP
To compute an array of illuminance contributions according to a Tregenza sky:
.IP "" .2i
rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
@render.opt -f tregenza.cal scene.oct < test.dat
.SH ENVIRONMENT
RAYPATH         path to search for -f and -M files
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)
Revision:	1.14
Committed:	Tue Oct 11 16:54:26 2005 UTC (19 years, 8 months ago) by greg
Branch:	MAIN
Changes since 1.13:	+8 -3 lines
Log Message:	Added rtcontrib -fo option to override new reluctance to clobber existing files
#	User	Rev	Content
1	greg	1.14	.\" RCSid "$Id: rtcontrib.1,v 1.13 2005/10/06 16:28:59 greg Exp $"
2	greg	1.3	.TH RTCONTRIB 1 5/25/05 RADIANCE
3	greg	1.1	.SH NAME
4	greg	1.5	rtcontrib - compute contribution coefficients in a RADIANCE scene
5	greg	1.1	.SH SYNOPSIS
6			.B rtcontrib
7			[
8			.B "\-n nprocs"
9			][
10	greg	1.14	.B \-fo
11			\|
12	greg	1.8	.B \-r
13			][
14	greg	1.1	.B "\-e expr"
15			][
16			.B "\-f source"
17			][
18	greg	1.7	.B "\-o ospec"
19	greg	1.1	][
20			.B "\-b binv"
21	greg	1.12	][
22			.B "\-bn nbins"
23	greg	1.1	]
24	greg	1.9	{
25			.B "\-m mod \| \-M file"
26			}
27			..
28	greg	1.1	[
29			.B $EVAR
30			]
31			[
32			.B @file
33			]
34			[
35			rtrace options
36			]
37			.B octree
38	greg	1.4	.br
39			.B "rtcontrib [ options ] \-defaults"
40	greg	1.1	.SH DESCRIPTION
41			.I Rtcontrib
42			computes ray contributions (i.e., color coefficients)
43			for objects whose modifiers are named in one or more
44			.I \-m
45			settings.
46	greg	1.2	These modifiers are usually materials associated with
47			light sources or sky domes, and must directly modify some geometric
48			primitives to be considered in the output.
49	greg	1.9	A modifier list may also be read from a file using the
50			.I \-M
51			option.
52	greg	1.10	The RAYPATH environment variable determines directories to search for
53			this file.
54			(No search takes place if a file name begins with a '.', '/' or '~'
55			character.)\0
56	greg	1.9	.PP
57	greg	1.3	The output of
58			.I rtcontrib
59			has many potential uses.
60			Source contributions can be used as components in linear combination to
61	greg	1.1	reproduce any desired variation, e.g., simulating lighting controls or
62			changing sky conditions via daylight coefficients.
63			More generally,
64			.I rtcontrib
65	greg	1.3	can be used to compute arbitrary input-output relationships in optical
66			systems, such as luminaires, light pipes, and shading devices.
67	greg	1.1	.PP
68	greg	1.2	.I Rtcontrib
69			calls
70			.I rtrace(1)
71	greg	1.5	with the -oTW option to calculate the daughter ray
72			contributions for each input ray, and the output tallies
73	greg	1.7	are sent to one or more destinations according to the given
74	greg	1.1	.I \-o
75			specification.
76	greg	1.7	If a destination begins with an exclamation mark ('!'), then
77			a pipe is opened to a command and data is sent to its standard input.
78			Otherwise, the destination is treated as a file.
79	greg	1.14	An existing file of the same name will not be clobbered, unless the
80			.I \-fo
81			option is given.
82			If instead the
83	greg	1.8	.I \-r
84	greg	1.14	option is specified, data recovery is attempted on existing files.
85	greg	1.2	If an output specification contains a "%s" format, this will be
86	greg	1.1	replaced by the modifier name.
87			The
88			.I \-b
89			option may be used to further define
90	greg	1.2	a "bin number" within each object if finer resolution is needed, and
91			this will be applied to a "%d" format in the output file
92	greg	1.1	specification if present.
93	greg	1.3	The actual bin number is computed at run time based on ray direction
94			and surface intersection, as described below.
95	greg	1.12	If the number of bins is known in advance, it should be specified with the
96			.I \-bn
97	greg	1.13	option, and this is critical for output files containing multiple values
98			per record.
99			Since bin numbers start from 0, the bin count is always equal to
100			the last bin plus 1.
101			Set the this value to 0 if the bin count is unknown (the default).
102	greg	1.1	The most recent
103	greg	1.12	.I \-b,
104			.I \-bn
105	greg	1.1	and
106			.I \-o
107	greg	1.2	options to the left of each
108	greg	1.1	.I \-m
109	greg	1.2	setting affect only that modifier.
110			(The ordering of other options is unimportant.)\0
111	greg	1.1	.PP
112	greg	1.2	If a
113			.I \-b
114			expression is defined for a particular modifier,
115			the bin number will be evaluated at run time for each
116			ray contribution from
117			.I rtrace.
118			Specifically, each ray's world intersection point will be assigned to
119			the variables Px, Py, and Pz, and the normalized ray direction
120			will be assigned to Dx, Dy, and Dz.
121			These parameters may be combined with definitions given in
122			.I \-e
123	greg	1.3	arguments and files read using the
124	greg	1.2	.I \-f
125	greg	1.3	option.
126			The computed bin value will be
127	greg	1.2	rounded to the nearest whole number.
128			This mechanism allows the user to define precise regions or directions
129			they wish to accumulate, such as the Tregenza sky discretization,
130			which would be otherwise impossible to specify
131			as a set of RADIANCE primitives.
132	greg	1.3	The rules and predefined functions available for these expressions are
133			described in the
134			.I rcalc(1)
135			man page.
136	greg	1.6	Unlike
137			.I rcalc,
138			.I rtcontrib
139			will search the RADIANCE library directories for each file given in a
140			.I \-f
141			option.
142	greg	1.1	.PP
143			If no
144			.I \-o
145			specification is given, results are written on the standard output in order
146			of modifier (as given on the command line) then bin number.
147	greg	1.7	Concatenated data is also sent to a single destination (i.e., an initial
148	greg	1.2	.I \-o
149			specification without formatting strings).
150	greg	1.1	If a "%s" format appears but no "%d" in the
151			.I \-o
152			specification, then each modifier will have its own output file, with
153			multiple values per record in the case of a non-zero
154			.I \-b
155			definition.
156			If a "%d" format appears but no "%s", then each bin will get its own
157			output file, with modifiers output in order in each record.
158			For text output, each RGB coefficient triple is separated by a tab,
159			with a newline at the end of each ray record.
160			For binary output formats, there is no such delimiter to mark
161			the end of each record.
162			.PP
163	greg	1.2	Input and output format defaults to plain text, where each ray's
164			origin and direction (6 real values) are given on input,
165			and one line is produced per output file per ray.
166			Alternative data representations may be specified by the
167			.I \-f[io]
168			option, which is described in the
169			.I rtrace
170			man page along with the associated
171			.I \-x
172			and
173			.I \-y
174			resolution settings.
175			In particular, the color ('c') output data representation
176			together with positive dimensions for
177			.I \-x
178			and
179			.I \-y
180			will produce an uncompressed RADIANCE picture,
181			suitable for manipulation with
182			.I pcomb(1)
183			and related tools.
184	greg	1.1	.PP
185			If the
186			.I \-n
187			option is specified with a value greater than 1, multiple
188	greg	1.2	.I rtrace
189	greg	1.1	processes will be used to accelerate computation on a shared
190			memory machine.
191			Note that there is no benefit to using more processes
192	greg	1.2	than there are local CPUs available to do the work, and the
193			.I rtcontrib
194			process itself may use a considerable amount of CPU time.
195	greg	1.1	.PP
196			Options may be given on the command line and/or read from the
197			environment and/or read from a file.
198			A command argument beginning with a dollar sign ('$') is immediately
199			replaced by the contents of the given environment variable.
200			A command argument beginning with an at sign ('@') is immediately
201			replaced by the contents of the given file.
202	greg	1.2	.SH EXAMPLES
203			To compute the proportional contributions from sources modified
204			by "light1" vs. "light2" on a set of illuminance values:
205	greg	1.1	.IP "" .2i
206	greg	1.2	rtcontrib -I+ @render.opt -o c_%s.dat -m light1 -m light2 scene.oct < test.dat
207			.PP
208			To generate a pair of images corresponding to these two lights'
209			contributions:
210	greg	1.1	.IP "" .2i
211	greg	1.2	vwrays -ff -x 1024 -y 1024 -vf best.vf \|
212			rtcontrib -ffc `vwrays -d -x 1024 -y 1024 -vf best.vf`
213			@render.opt -o c_%s.pic -m light1 -m light2 scene.oct
214			.PP
215			These images may then be recombined using the desired outputs
216			of light1 and light2:
217	greg	1.1	.IP "" .2i
218	greg	1.2	pcomb -c 100 90 75 c_light1.pic -c 50 55 57 c_light2.pic > combined.pic
219	greg	1.1	.PP
220	greg	1.2	To compute an array of illuminance contributions according to a Tregenza sky:
221			.IP "" .2i
222	greg	1.11	rtcontrib -I+ -b tbin -o sky.dat -m skyglow -b 0 -o ground.dat -m groundglow
223	greg	1.2	@render.opt -f tregenza.cal scene.oct < test.dat
224	greg	1.6	.SH ENVIRONMENT
225	greg	1.10	RAYPATH path to search for -f and -M files
226	greg	1.1	.SH AUTHOR
227			Greg Ward
228			.SH "SEE ALSO"
229			cnt(1), getinfo(1), pcomb(1), pfilt(1), ra_rgbe(1),
230			rcalc(1), rpict(1), rtrace(1), vwrays(1), ximage(1)